STUDIES ON THE ROOT GROWTH OF WHEAT VARIETIES G.S. SIROHI, D.C. UPRETY and O.P.S. TOMAR

STUDIES ON THE ROOT GROWTH OF WHEAT VARIETIES G.S. SIROHI, D.C. UPRETY and O.P.S. TOMAR

Division of Plant Physiology, Indian Agricultural Research Institwe, New Delhi-lIOOn Received on March 6, 1977

SUMMARY

Twelve wheat varieties, C 306, C 591, NP 824. NP 846, NP 890, HD 1553, HD 1593,

HD 1949, HD 1977, HD 1981, HD 2009 and HD 2122 were studied for their root

characters. It was observed that there are potential genotypes which produce better lateral root system to support suitable shoot growth to give higher yield under moisture stress condition. Positive correlation of lateral root length with shoot growth and grain yield 'under moisture stress condition, indicate that such genotypes may be used for producing

high yielding varieties for rainfed condition.

INTRODUCTION

Growth behaviour of wheat varieties with respect to moisture stress has been investigated earlier in this laboratory (Asana, 1957; 1961), however, studies concerning root growth are inadequate. Asana and Singh (1967) studied the relation between flowering time and root growth. They observed an association between early flowering and root growth. Subbiah et al., (1968) demonstrated differences in the root growth of tall and semi-dwarf varieties. They reported that the root system of some semi-dwarf wheats (Sonora 64), penetrates deeper than that of the taller varieties. The roots of other semi-dwarf types (Lermo Rojo) spreads laterally and are mostly confined to the upper 15 cm of soil.

Although a large wheat growing area in this country remains under moisture stress condition and the water supply to plants largely depends on its root system yet the studies on the root system of wheat varieties have been inadequate.

The main aim of the present study, therefore, was to investigate the pattern of root development of wheat varieties under rainfed (different moisture conditions) in the field. Attempts were also made to find varietal differences in root growth pattern.

MATIlRIAL AND METHODS

Seeds of twelve wheat varieties, C 306, C 59], NP 824, NP 846, NP 890, HD 1553, HD 1593. HD 1949, HD 1977, HD 1981, HD 2009 and HD 2122 were sown in 10 field plots arranged in four randomized blocks of three replicates. Wheat in the irrigated block were given 5 irrigations whereas those grown in the un irrigated block were not irrigated

G.S. SIROHI, D.C. UPRETY AND O.P.S. TOMAR

186

Roots were dug out and collected at three stages of growth i.e. 35, 55 and 75 days after sowing from an area of 2' x2' to a depth of 2.5'. Soil was separated from roots first by gently washing them. Roots were further washed over a fine sieve. Observations for the length and number of seminal and lateral roots, fresh and dry weight of roots were recorded periodically. Relative extension rate of the roots was calculated by the method reported earlier (Tennant 1976). Data for number of tillers, fresh and dry weight of shoots, height of plants, grain yield and other yield attributes were also recorded. The data were statistically analysed following the method of analysis of variance of Kempthom (1957). The correlations of root characters such as seminal root length, lateral root length, lateral root number, fresh and dry weight of total roots with tiller number, fresh and dry weight of shoot, height of plant, ear number/sq. meter, grain yield/sq. meter and yield/5 plants were also computed.

RESULTS

It is noted (Fig. 1) that the length of seminal roots was significantly more in NP 846, HD 1949, HD 1553, C 591 and HD 1977 at 35 days. However, HD 1981, HD 1553 NP 846 and NP 890 maintained comparatively longer root at later stages of growth. The varietal differences were more pronounced in the later stages of observations. The effect of unirrigated conditions on the elongation of seminal root was not significant in the initial stage of growth (35 days after sowing), however, in the later two stages, the seminal roots penetrated deeper under unirrigated condition. This was further confirmed by the

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C U L T I V A R S

• ~IO. 1. Cu~ilinear representation of the root length of 12 wheat cultivars under irrigated

and unlrrIgated condItIOns after 35, 55, and 75 days of growth.

(1) HD 2122, (2) HD 2009, (3) HD 1981, (4) HD 1949. (5) HD 1593 (6) HD 1553 (7) C 306

(8) C 591, (9) NP 824, (10) NP 846, (ll) NP 890 and (12) HD 1977. ' , ,

- x - - x - -Irrigated

-- ---,"* *«"'4$"".* ii$Uf'lC4'.'" 4 . w aM lat:, ~ Table 1. Relative exteMion rate of seminal and lateral roots of wheat varieties (g., Day) Days after Treatment HD HD HD HD HD HD C C NP NP NP HD sowing 2122 2009 1981 1949 1593 1553 306 591 824 846 890 1977

S E M

Unirrigated 0.0235 0.0245 0.0301 0.0203 0.0241 0.0290 0.0222 0.0255 0.0227 0.0182 0.0249 0.0182 I 55-35

N A

Irrigated 0.0224 0.0208 0.0215 0.0173 0.0206 0.0189 0.0240 0.0166 0.0250 0.0173 0.0253 0.0200

~

L R

.,

Unir~igated

0.0055 0.0045 0.0002 0.0035 0.0030 0.0001 0.0029 0.0007 0.0001 0.0017 0.0034 0.0098

0 ~

0 75-55

~

0 Irrigated 0.0070 0.0040 0.0001 0.0002 0.0026 0.0002 0.0020 0.0010 0.0002 0.0009 0.0030 0.0077

::c

T ~

---­

L A

Unirrigated 0.0055 0.0079 0.0051 0.0135 0.0074 0.0173 0.0206 0.0063 0.0036 0.0018 0.0007 0.0017

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55·35

~

E R

Irrigated 0.0202 0.0136 0.0130 0.0160 0.0121 0.0179 0.0195 0.0130 0.0146 0.0155 0.0190 0.0129

A L R

Unirrigated 0.0053 0.0015 0.0011 0.0087 0.0064 0.0090 0.0040 0.0065 0.0009 0.0008 0.0037 0.0007

o

75-55

0 T

Irrigated 0.0059 0.0049 0.0082 0.0065 0.0092 0.0098 0.0069 0.0079 0.0055 0.0104 0,0056 0.0027

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188 G.S. SIROHI, D.C. UPRETY AND O.P.S. TOMAR

data on 'relative extension rate' of seminal roots. The root extension rate was also consi­ derably higher under unirrigated condition as compared to irrigated one (Table I).

From the data on the elongation of lateral roots, it was observed that the length of lateral roots of varieties HD 1949, HD 1553, C 306 and NP 824.was significantly more than those of the varieties HD 2009, HD 1981, HD 1593 and NP 846 in all the stages of growth. There was a marked reduction in the elongation of lateral roots under unirri­ gated condition, however, the reduction was only 20 to 30% in HD 1949 and HD 1553 as compared to 60 to 80% in HD 2122, HD 1593, NP 846 _and NP 890, (Fig. 1). Varietal variation in the relative extension rate of lateral roots also showed similar trend as that observed in the elongation of lateral roots. Considerable reduction was observed in the extension rate of lateral roots of the varieties under unirrigated situation. However, in the case of HD 1553 and HD 1949 the extension growth rate oflateral roots under unirrigated condition was also quite high.

There was significantly higher number of lateral roots present in HD 2122, HD 1981, NP 824 and NP 846 in comparison to other varieties, however, the effect of treatment was not 'significant (Fig. 2).

NUMBER OF LATERAL ROOTS

29" 0-940-05310

'gt~~~

35 3

1

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A 2-13 N,S 5-53

2 _10~·\.~

~<7?O""

·1 2 3 4-" 5 6 7 8 9 10 II 12 C ·u L T 1 V A R S

FIG. 2. Curvilinear representation of the number of lateral roots of 12 wheat cultivars under irrigated and unirrigated conditions after 35, 55 and 75 days of growth.

The fresh weight of roots ofHD 1949 and HD 1553 was higher at all the sampling stages, whereas in case of HD 1593, C 306, C 591 and NP 824 the weight was higher in the later stages of growth only. The fresh weight of roots under unirrigated condition was significantly lower than that of those grown under irrigated condition at all the stages of growth (Fig. 3). Interaction was not significant. Dry weight of roots also showed more or less similar trend as observed for the fresh weight.

There was a marked varietal difference in the production of tillers. Tiller number ranged from 1.41 (HD 2122) to 3.383 (C 306). The production of tillers was significantly lower under unirrigated condition throughout the growth span of plants (Fig. 4). The reduction due to the moisture stress was 13% in C 306, 18% HD 1553,23% HD 1949 as

Note: Varieties namely HD 2122, HD 2009, HD 1981, HD 1949. HD 1593, HD 1553, C 306,

C 591, NP 824, NP 846, NP 890 aDd HD 1917 are referred as numbers I to 12 in this order respectively. Numbers given at the right hand side of curves denote the C.D. at 5% on the same pattern as given in

3-0

ROOT GROWTH OF WHEAT 189

DRY WEIGHT

I'RESH WEIGHT 0-4

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I 2 :3 4 5 6 7 e 9 10 II 12 C U L T I V A R S

FIG. 3. Curvilinear representation of the fresh and dry weight of root of 12 wheat cultivars under unirrigated and irrigated conditions after 35,55 and 75 days of growth.

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FlO. 4. Curvilinear representation of the shoot height and. tiller numbers of 12 wheat cultivars under irrigated and unirrigated conditions after 35, 55 and 75 days of growth.

compared to 64% in HD 1593 and 80% in NP 846 at 55 days. It was 20 to 35% in HD 1553, HD 1949 and C 591 and 60 to 70% in HD 1593 and NP 890 at 75 days. The height of plants of C 591, NP 846 and NP 890 was significantly more than those of other varieties. Plant height was significantly lower under unirrigated condition in all the varieties at all the stages of growth.

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190 O.S. SIROHI; D.C. UPRETY AND O.P.S. TOMAR

The fresh weight of shoot was considerably lower under unirrigated condition. The reduction was not very marked in HD 1553, C 306, and NP 824 but it was conspicuous in other varieties (Fig. 5). The dry weight of shoot varied considerably. It was compara­ tively higher in HD 1981, HD 1949, HD 1553 and C 306 at all the stages of growth. It was significantly lower under unirrigated condition. The interaction was significant only at 55 days. The reduction caused by unirrigated condition was not significant in HD 1949, HD 1553, C 306 and NP 824.

DRY WEIGHr

FRESH

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WEIGHr SHOOT

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FIG. 5. Curvilinear representation of the fresh and dry weight of shoot of 12 wheat cultivars under irrigated and unirrigated conditions after 35, 55 and 75 days of growth.

The number of ears per square meter varied significantly from 207 (HD 1593) to 297 (C 591). C 591, HD 2009, NP 824 and HD 1949 had comparatively higher ear number (Table II). Unirrigated condition significantly reduced the production of ears in all the varieties. The reduction was 24% (HD 1553),26% (HD 1949) and 29% (NP 824 and HD 2122) as compared to 60% in HD 1593 and 54% in NP 846. The interaction was not significant.

Grain yield per square meter significantly varied from 246.33 g (NP 824) to 368.5 g (HD 1593) and 351.3 g (HD 1981). There was significant reduction in the yield under unirrigatcd condition. The reduction was 50 to 60 per cent in NP 846, NP 824, HD 2122 and HD 1977. The depression was comparatively less in HD 1949 and HD 1553. Signifi­ cant varietal differences were observed in the yield per 5 plants. It was higher in HD 2009, C 591 and C 306 as compared to HD 2122, HD 1981, NP 846 and NP 890. A significant reduction in yield per plant was observed under unirrigated condition .. The reduction was 30 to 50 per cent in HD 1593, NP 846 and NP 890 and 18 to 25% in HD

1949, NP 824, HD 2099, HD 1553 and HD 1977.

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Table II. Yield characters of wheat varieties Characters Treatment HD HD HD HD HD HD C C NP NP NP HD 2122 2009 1981 1949 1593 1553 306 591 824 846 890 1977 Number of ear heads per sq. metre Unirrigated 195.00 Irrigated 267.66

200.33 357.33 186.00 302.33 220.66 308.66 118.00 297.00 218.33 288.00 187.00 281.66 204.33 390.00 223.66 316.33 158.66 341.33 160.66 319.33 160.00 28.6.33

§

0 ill:!

C.D. at 5% P. Grain yield

Variety Unirrigated

181.33

19.75 _199.66 Treatment 229.00

244.66

5.58

189.00

Interaction 241.50

266.76

N.S. 247.93

193.33

186.83

157.33

188.33

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>-! ::r: 0

per sq. metre Irrigated 373.50 477.83 473.76 332.00 548.00 335.33 416.30 436.10 299.33 375.83 384.50 385.33 "'1 (g) C.D. at 5% P. Variety 22.52 Treatment 28.75 Interaction 74,09

~ ::r: ttl > >-!

Grain yield Unirrigated 14.76 19.83 15.00 16.86 13.83 16.93 17.10 17.86 17.73 12.16 11.40 16.83 Per 5 plants (g) Irrigated 23.00 25.50 22.36 21.23 26.00 22.66 28.96 24.70 21.60 22.50 21.16 22.00 C.D. at 5% P. Variety 1.05 Treatment 1.09 Interaction 3.47

....

-0

....

192 G.S. SIROHI, D.C. UPRETY AND O.P.S. TOMAR

condition lateral root length was also correlated positive1y with ear number and grain yield per sq. meter. Lateral root number was negatively correlated with the tiller number, fresh and dry weight of shoot and the grain yield. However, this negative association was found significant only at 55 and 75 days.

Under unirrgated condition the seminal root length was negatively correlated with tiller number and grain yield. This correlation was weak and restricted to the later stages of growth. Fresh and dry weight of roots were positively correlated with the production of tillers and fresh and dry weight of shoots. This association was found only in the later stages of growth.

Table III. Correlation of root characters with those of shoot characters and yield of wheat varieties

(35 days after sowing)

Unirrigated Shoot Shoot Shoot Shoot Ear No./ Yield/ Yield/

Days after No. fresh dry height sq. m. sq.m. 5 plants

sowing weight weight

2 3 4 5 6 7 8

35 0.345 0.055 -0.409 -0.141 -0.471 -0.297 -0.549· Seminal

55 0.157 0.276 0.425 0.145 -0.130 0.069 -0.378 root

75 -0.031 -0.030 0.024 -0.138 -0.508 -0.295 -0.459 length

35 0.715·· 0.599· 0.666· 0.231 0.218 0.379 - .191 Lateral

55 0.489 0.660· 0.628· 0.330 0.607· 0.644· .347 root

75 0.424 0.610· 0.641· 0.210 0.626· 0.553· .283 length

35 0.496 0.411 0.030 0.371 -0.104 -0.275 -0.499 Lateral

55 -0.398 -0.557· -0.655· 0.004 -0.337 -0.609· 0.009 root

75 -0.476 -0.335 -0.499 0.037 -0.285 -0.533 -0.351 number

35 0.028 0.266 0.296 0.252 0.313 0.268 0.122 Fresh

55 0.548· 0.502 0.314 -0.001 0.023 0.633· 0.036 weight of

75 0.463 0.337 0.193 0.199 0.017 0.376 0.117 root

35 -0.350 0.055 0.241 -0.033 0.329 0.290 0.044 Dry

55 0.249 0.417 0.409 -0.081 0.362 0.759·· 0.320 weight 0"

75 0.239 0.302 0.305 0.169 0.489 0.577· 0.568 root

Irrigated

35 0.027 0.331 0.596· -0.153 0.213 -0.303 -0.198 Seminar

55 0.158 0.440 0.509 0.555· -0.363 -0.535 -0.582· root

75 -0.188 -0.032 0.104 0.373 -0.558· -0.332 -0.423 length

35 0.177 0.251 0.334 0.043 0.432 -0.273 -0.016 Lateral

55 -0.002 0.488 0.645· 0.141 -0.161 -0.668· -0.320 root

75 0.071 0.531 0.592· 0.315 0.095 -0.548· -0.194 length

35 0.230 0.292 0.103 0.205 0.196 -0.084 -0.096 Lateral

55 0.207 0.099 -0.135 0.224 0.432 -0.057 0.001 root

75 0.527 0.524 0.167 0.178 0.041 -0.062 -0.075 number

35 0.327 0.653· 0.625· 0.141 0.224 -0.604· -0.406 Fresh

55 0.421 0.399 0.329 -0.129 -0.174 0.234 0.51 weight of

\i

I; 75 0.178 0.196 0026 -0.11& 0.274 0.197 .610· root

1

. ~

ROOT GROWTH OF WHEAT ₁₉₃

2 3 4 5 6 7 8

1

,

_{35 0.504 0.641- 0.525}

0.303 0.116 -0.256 -0.367 Dry

55 0.354 0.320 0.273 -0.222 -0.282 +0.022 -0.118 weight of

~

.

75 0.028 0.269 0.019 -0.009 0.224 -0.133 0.081 root

Unirrigated (55 days after sowing)

35 -0.323 0.331 0.355 -0.141 -0.471 -0.292 -0.550* Seminal

55 -0.139 -0.154 -0.040 0.309 -0.130 0.069 0.147 root

75 -0.503 -0.253 -0.389 0.025 -0.508 -0.293 -0.460 length

35 0.509 0.619- 0.549- 0.330 0.219 0.379 -0.191 Lateral

55 0.901·- 0.535 0.580- 0.384 0.607- 0.645- 0.347 root

75 0.814-- 0.369 0.427 0.308 0.626- 0.552- 0.283 length

35 -0.037 0.384 0.444 0.258 -0.104 -0.275 -0.499 Lateral

55 -0.551- -0.514 -0.558- -0.008 -O.3i7 -0.609- 0.009 root

75 -0.558- -0.500 -0.306 -0.133 -0.285 -0.533 0.351 number

35 0.052 0.270 0.370 0.081 0.313 0.268 0.122 Fresh

55 0.659- 0.594· 0.603- 0.099 0.023 0.633-

o

036 weight of

75 0.453 0.532 0.589- 0.148 0.017 0.375 0.117 root

35 0.060 -0.176 0.031 -0.100 0.330 0.290 0.044 Dry

55 0.783*- 0.235 0.353 0.034 0.362 0.759-· 0.320 weight of

75 0.670- 0.282 0.474 0.092 0.490 0.576- 0.568- root

Irrigated

35 0.229 0.420 0.090- -0.154 0.213 -0.303 -0.197 Seminal

55 0.419 -0.159 -0.197 0.681- -0.363 -0.535 -0.582- root

75 - 0.299 -0.590- -0.449 0.374 -0.558- -0.332 -0.423 length

35 0.299 0.1l3 0.174 -O.1l7 0.433 -0.273 -0.016 Lateral

55 0.348 -0.303 -0.215 0.099 -0.161 -0.668- -0.320 root

75 0.248 -0.436 -0.080 0.213 -0.095 -0.548* -0.194 length

35 0.232 0.131 0.401 -0.005 0.196 -0.084 -0.096 Lateral

5~ 0.239 0.015 0.251 0.009 0.432 -0.057 0.001 root

75 0.571- 0.263 0.324 -0.041 0.041 -0.063 -0.075 number

35 0.442 0.361 0.095 0.001 0.224 -0.604- -0.406 Fresh

S5 0.497 0.631- 0.141 -0.164 -0.174 0.234 0.050 weight

. 75 0.509 0.565'" 0.177 -0.106 0.274 0.196 0.161 of root

35 0.433 0.568- 0.306 0.073 0.1l7 -0.256 -0.367 Dry wt.

55 0.334 0.507 0.053 -0.155 0.282 0.021 -0.199 of

75 0.320 0237 -0.122 -0.029 0.224 -0.133 0.081 root

Unirrigated (75 days after sowing)

35 0.383 -0.088 -0.109 -0.138 -0.471 -0.297 -0.550· Seminal

55 -0.040- -0.107 -0.352 0.140 -0.130 0.069 0.147 root

75 0.469 -O.45S -0.617· -0.292 -0.508 -0.293 -0.460 length

-0.191 Lateral

35 0.502 0.S92· 0.61S· O.24S 0.219 0.379

SS 0.931·· 0.6S1· 0.866·- 0.125 0.607· 0.645· 0.347 root

75 0.821·- 0.480 0.791·· O.OSO 0.626· 0.S52· 0.283 length

-0.104 -0.275 -0.499 Lateral

-0.609- 0.009 root

35 0.073 0.447 0.165 0.21S

55 0.610- -0.324 -0.697" -0.107 -0.337

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-0.285 -0.533 -O.3S1 number

75 0.537 -0.416 -0.561· 0.118

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194 G.S. SIROm, D.C. UPRETY AND O.P.S. TOMAR

1 2 3 4 5 6 7 8

35 0.201 0.201 0.257 -0.188 -0.313 0.268 0.122 Fresh

55 0.675* 0.459* 0.595* 0.083 0.023 0.683* 0.036 weight

75 0.435 0.650* 0.402 0.661* 0.017 0.375 0.117 of root

35 0.199 -0.290 0.086 -0.167 0.330 0.290 0.044 Dry wt.

55 0.837** 0.224 0.659* -0.092 0.362 0.759** 0.320 of

75 0.687*· 0.590* 0.620* 0.511 0.490 0.576· 0.568* root

Irrigated

35 -O.l~ 0.082 0.521 -0.198 0.213 -0.303 -0.197 Seminal

55 0.386 0.018 -0.089 0.245 -0.363 -0.535 -0.582* root

75 0.169 -0.691· -0.571· 0.076 -0.558· -0.332 -0.423 length

35 -0.275 0.032 0.178 0.029 0.433 -0.273 ~0.0l6 Lateral

55 0.036 -0.227 0.200 -0.163 -0.161 -0.668* -0.320 root

75 0.048 -0.267 0.044 0.057 -0.095 -o,5~* -0.194 length

35 -0.094 0.104 0.097 0.068 0.196 -0.084 -0.096 Lateral

55 -0.157 0.166 0.119 0.447 0.432 -0.057 0.001 root

75 0,555* 0.574· 0.256 0.067 0.041 -0.063 -0.75 number

35 0.178 0.300 0.457 0.011 0.224 -0.604* -0.406 Fresh

55 0.606· 0.685·· 0.561· -0.280 0.174 0.234 0.050 weight

75 0.390 0.846*· 0.568 0.253 0.274 0.196 0.161 of root

35 0.219 0.432 0.251 0.100 0.117 -0.256 -0.367 Dry

55 0.783·· 0.540· 0.608· -0.453 0.282 0.021 -0.119 weight

75 0.284 0.682*· 0.354 0.387 0.224 -0.133 0.081 of root

The correlations of root characters were different under irrigated condition. Negative correlation was observed between seminal root length and the grain yield. This correlation was significant only at 55 days. The plant height was positively correlated with the seminal root length also at 55 days. Lateral root length was negatively correlated with the grain yield. This association was significant in the later two stages of sampling. Lateral root numbers did not have any strong correlation with shoot characters. Similar to unirrigated situation, the fresh and dry weight of roots were also positively correlated with the fresh and dry weight of shoots in irrigated condition. This correlation was signi­ ficant only at 55 and 75 days.

DISCUSSION

Twelve varieties of wheat included in the present study showed some interesting features in the nature of their root development. The varietal differences in the elongation of seminal roots were observed more in the later stages of growth. The elongation of the seminal roots was not adversely affected by un irrigated condition and it had no stron g correlations with shoot characters and yield. Tennet (1976) also observed that the inherent pattern of the seminal root length increase in wheat plants was largely main­ tained even when the nutrient supply was totally lacking. According to May et al., (1967)

develop­

) and Evans (1970) this may be due to the effect of rigid internal control of roo.!

f:

1

ROOT GROWTH OF WHEAT ₁₉₅

ment. The increase in seminal root length under unirrigated condition was due to the fact that the growth of seminal root was faster towards the moisture zone as compared to

nodal roots. This is noted by the considerably higher relative extension rate of seminal

\

roots under unirrigated condition.

The lateral root system did not express their differences under irrigated condition whereas under unirrigated condition the varietal differences were significantly marked. The lateral root length in HD 1553 and HD 1949 was comparatively less affected by unirrigated condition. This was also reflected in the production of tillers and the grain yield of these varieties. The highly positive correlation of lateral root length with that of shoot number (0.93 and 0.82) and the fresh and dry weight of shoot and grain yield and its components (0.62 and 0.55) in unirrigated condition was observed in the present investigation. This observation was in agreement with that of Hackett (1969) who described the nodal root system as to reflect plant response. He has also observed the greater dependence of development of nodal roots on the moisture of the rhizosphere. In the cases of HD 1553 and HD 1949. where the elongation growth of lateral roots were better under unirrigated situation, the tiller survival and the grain yield were not much affected by the low moisture condition. It was also clear that under irrigated condition the varietal differences in the roots did not reflect much on the growth and yield of wheat varieties. In that case the seminal and lateral roots got their water supply immediately below the surface and there was no competition. However, under un irrigated condition though the seminal roots grew deeper and took responsibility for the survival and growth of mother shoot, the lateral roots supplied moisture to the nodal tillers (Troughton, 1962). If the lateral roots were shorter as in the cases of NP 846 and HD 1593 the tiller survival was poor resulting in the low dry matter accumulation and lower grain yield whereas if lateral roots grew deeper as observed in case of HD 1949, HD 1553, C 306 etc. Tbey continued to supply moisture to the nodal tillers for their survival thereby resulting in more yield.

It was clear from these observations that within the wheat varieties there are potential genotypes which can produce good lateral root system under moisture stress condition to support shoot growth and provide better grain yield. Further the positive correlations of lateral root length with the shoot characters and yield indicated the feasibility of considering the lateral root elongation as one of the criteria for selecting wheat varieties for moisture stress conditions.

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Asana, R.D. (1957). The problem of assessment of drought resistance in crop plants. Indian I. Genet. 17: 310-78.

----(1961}. Analysis of drought resistance in wheat. Arid Zone Research, 16: 183-90.

Evans, P.S. (1970). Root growth of Lolium perenne (L) 1. Effect of plant age, seed weight and nutrient concentration on root weight, length and number of apices. New Zealand I. Bot., 8: 344-56. Backett, C. (1969). Quantitative aspects of growth of cereal root systems. 'Root Growth' (Ed.) Whittington,

W.J. Butterworths, London, P. 134·45.

}day. L.B., Randles, F.B., Aspinall, D and Paleg, L.G. (1967). Quantitative studies on root development

(ii) Growth in the early stages of development. Aust. I. Bioi. Sci., 20: 273-83.

Kempthorne, O. (1957). All introduction to Genetic StatistiCS, pp. 1st Ed. 287-304. John Wiley & Sons Inc.

New York.

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196 O.S. SIROHl, D.C. UPRETY, AND O.P.S. TOMAR

Subbiah, B.V., Katyal, J.C., Narasinham.R.L. and Dakshinamurti, C. (1968). Preliminary investigations on root distribution of high yielding wheat varieties. International J. Appl. Radiation & Isotope,

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Tennant, D. (1976). Root growth of wheat. I. Early patterns of multiplication and extension of wt.eat roots including effects of levels of nitrolen, phosphorus and potassium. Aust. J. Agrie. Res.,

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Troughton, A. (1962). The roots of temperate cereals (wheat, barley. oats and rye). Commonwealth Bureau of Pastures and Field Crops Mimeographic publication No.2.

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